When a guitarist plays a guitar with standard string tuning and the standard physical configuration (left hand selecting notes on the fretboard and right hand strumming the strings), a downstrum (in which the right hand strokes downward) generally produces an ascending arpeggiated chord. An upstrum generally produces a descending arpeggiated chord. Generally, a guitarist will alternate up and downstrums, producing arpeggiated chords which are alternately ascending and descending. This action is easy, smooth and natural, due to the fact that two chords may be produced with a single up-down cycle of the right hand. This two-chord-per-cycle technique enables a guitarist to easily produce strums in rapid succession. Also, this technique allows a guitarist to easily introduce a swing factor into the timing of the strums. A swing factor or “feel” is present when the elapsed time between an upstrum and a downstrum is different than the elapsed time between a downstrum and an upstrum. By consistently alternating strums with the same time difference, a guitarist can produce a desired swing feel. A guitarist may easily achieve this effect by simply displacing the center of his stroke either slightly above or slightly below the vertical center of the six strings (the vertical center of the strings is between the D and G strings). This displacement of stroke is so easy and natural that guitarists are often not even aware that they are doing it.
Various known prior art processing systems enable a keyboardist to simulate guitar strums. However, these prior art systems have been found to be lacking in the above stated advantageous qualities which a guitar possesses.
For example, U.S. Pat. No. 4,379,420 (Deutsch) describes a keyboard guitar emulator in which a group of keys perform the dual function of chord selection and arpeggiated chord triggering. In text column 11, lines 44-68, an alternating strum direction feature is disclosed. A musician, or user, may trigger a first strum by depressing a chord on the keyboard. Once the chord is depressed and held, an additional strum, alternating in direction, may be triggered by lifting any key within the chord and re-pressing it. Since a chord is triggered only when the key moves from rest to depressed position, the two-chord-per-cycle technique described above is not possible and the above described advantages of this technique are not realized.
Other guitar emulators provide a separate trigger switch to trigger arpeggiated chords, e.g., U.S. Pat. No. 3,967,520 (Drydyk), but none of the known prior art enables a user to produce arpeggiated chords in alternating directions with the same easy, smooth, and natural action of strumming a guitar.